Financial crises can have a severe impact on the real side of the economy with countries losing up to 20 percent of GDP. The paper studies rules that prevent financial instability and currency crises. These include institutional arrangements for a solid banking system, prudent regulations and appropriate principles of monetary policy. The paper studies the role of the IMF in light of the past experience in preventing currency crises and a systemic breakdown of the world's financial system and points out necessary IMF reforms. It discusses how the IMF should adjust to the structural changes in the world economy.